Experimental support for WebExtensions (in gecko-target mode). Please note that this support will be dropped soon.

Support for ALSA on Linux.

Support for WebAssembly (WASM).

Support for advanced Graphite font shaping features.

Support for modern web cryptography: up to TLS 1.3, modern ciphers, HSTS, etc.

Important differences with Mozilla Firefox:

Uses Goanna as a layout and rendering engine. Goanna behaves slightly differently than Gecko in certain respects and may result in different display of web pages. e.g.: Goanna renders gradients in a more accurate color space (non-premultiplied).

Builds on UXP, our XUL platform in development. As such XUL is alive and well in this browser and will not be deprecated.

Has some long-standing known issues with the Mozilla code-base fixed (e.g. CVE-2009-1232).

Does not use Rust or the Photon user interface. You can expect a familiar interface as-carried by Firefox between v29 and v56.